Position-measuring devices are used to determine, with extreme precision, the relative position of a fixed point with respect to a moving point in space, usually via distance measurements and/or angle measurements. In this context, the moving point in space is assigned a measuring reflector, with which a beam of rays of the optical position-measuring device is aligned, and which is tracked in the course of the measurement. The position of the measuring reflector, and therefore the position of the moving point in space, may be determined based on the distance information and/or angle information obtained in this manner.
An optical position-measuring device is described in European Patent No. 0 919 830. This device has a light source, a stationary reference reflector, a measuring reflector movable in space, a detection unit and a light-beam deflection unit. A beam of rays emitted by the light source is able to be aligned in the direction of the measuring reflector via the light-beam deflection unit. To that end, the light-beam deflection unit includes a slide unit, which is mounted in a manner allowing it to swivel about the spherical reference reflector in a cardan system. The midpoint of the spherical reference reflector represents a fixed reference point. Furthermore, the light source, the detection unit as well as further components, which are necessary for the interferometric distance measurement between the reference reflector and the measuring reflector, are swiveled with the slide unit, as well. This arrangement has the disadvantage that components having mass, such as the light source, the detection unit, etc., which are also necessary for the interferometric distance measurement, must be swiveled together with the slide unit about the fixed reference point. This increases the demands on the support of the slide unit considerably.
If, as an alternative in such a device, it is provided to dispose the light source and/or the detection unit outside of the slide unit and, in each instance, to transmit the light beams via optical fibers, then further problems result. They are caused due to the fact that such optical fibers allow only a certain bending radius. As a consequence of the only relatively large bending radii allowed, the required space for such a device increases considerably.